gmtoff: MS CRT implementation of _tzset() (and _timezone) assumes that >0
represent positions west of the Prime Meridian. This module assumes the
opposite, so flip the sign of 'timezone' when compiling for mingw.
gmtoff x = do
dst <- (#peek struct tm,tm_isdst) x
tz <- peek timezone
gmtoff x = do
dst <- (#peek struct tm,tm_isdst) x
tz <- peek timezone
+#if defined(mingw32_TARGET_OS)
+ -- According to the MSVC documentation for _tzset, _timezone is > 0
+ -- for locations west of the Prime Meridian. Code elsewhere in this
+ -- module assume that >0 gmt offsets means east, so flip the sign.
+ tz <- return (-tz)
+#endif
if dst then return (fromIntegral tz - 3600) else return tz
# endif /* ! HAVE_ALTZONE */
#endif /* ! HAVE_TM_ZONE */
if dst then return (fromIntegral tz - 3600) else return tz
# endif /* ! HAVE_ALTZONE */
#endif /* ! HAVE_TM_ZONE */